The Dynamics and Heating of Active Region Loops

Abstract

I examine the dynamics of active regions using spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. I show the relationship between non-thermal velocities, Doppler outflows and downflows, intensities, and electron density for two representative active regions out of a group of 18 active regions examined. Results from the other active regions are summarized. Imaging spectra of these active regions were obtained from a number of different EIS raster observations. In the case of the outflows for the two representative regions, two-Gaussian fits were made to line profiles of Fe XII and Fe XIII to obtain quantitative information on high-speed components of the outflows. A three-Gaussian fit was made for the Fe XII line at λ195.119. The highest speed outflows occur in weak regions adjacent to the bright loops in active regions. They are weak (less than 5% of the intensity of the main spectral component in the brightest parts of active regions) and even in the extensive flow regions they are generally less than 25% of the intensity of the main component. The outflow regions are characterized by long or open magnetic field lines and I suggest that the apparent absence of these higher speed outflows in bright regions is due to abundant stationary plasma in the closed bright loop regions that mask or overwhelm the outflow signal.